/*
 * Copyright 2018 data Artisans GmbH Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License. You may obtain a copy of the
 * License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed
 * to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 */

package com.dataartisans.flinktraining.solutions.datastream_java.windows;

import com.dataartisans.flinktraining.exercises.datastream_java.datatypes.TaxiFare;
import com.dataartisans.flinktraining.exercises.datastream_java.sources.TaxiFareSource;
import com.dataartisans.flinktraining.exercises.datastream_java.utils.ExerciseBase;
import org.apache.flink.api.java.tuple.Tuple3;
import org.apache.flink.api.java.utils.ParameterTool;
import org.apache.flink.streaming.api.TimeCharacteristic;
import org.apache.flink.streaming.api.datastream.DataStream;
import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;
import org.apache.flink.streaming.api.functions.windowing.ProcessWindowFunction;
import org.apache.flink.streaming.api.windowing.time.Time;
import org.apache.flink.streaming.api.windowing.windows.TimeWindow;
import org.apache.flink.util.Collector;

/**
 * Java reference implementation for the "Hourly Tips" exercise of the Flink training
 * (http://training.ververica.com).
 *
 * The task of the exercise is to first calculate the total tips collected by each driver, hour by
 * hour, and then from that stream, find the highest tip total in each hour.
 *
 * Parameters: -input path-to-input-file
 *
 */
public class HourlyTipsSolution extends ExerciseBase {

    public static void main(String[] args) throws Exception {

        // read parameters
        ParameterTool params = ParameterTool.fromArgs(args);
        final String input = params.get("input", ExerciseBase.pathToFareData);

        final int maxEventDelay = 60;       // events are out of order by max 60 seconds
        final int servingSpeedFactor = 600; // events of 10 minutes are served in 1 second

        // set up streaming execution environment
        StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
        env.setStreamTimeCharacteristic(TimeCharacteristic.EventTime);
        env.setParallelism(ExerciseBase.parallelism);

        // start the data generator
        DataStream<TaxiFare> fares = env.addSource(
                fareSourceOrTest(new TaxiFareSource(input, maxEventDelay, servingSpeedFactor)));

        // compute tips per hour for each driver
        DataStream<Tuple3<Long, Long, Float>> hourlyTips = fares
                .keyBy((TaxiFare fare) -> fare.driverId).timeWindow(Time.hours(1))
                .process(new AddTips());

        DataStream<Tuple3<Long, Long, Float>> hourlyMax = hourlyTips.timeWindowAll(Time.hours(1))
                .maxBy(2);

        // You should explore how this alternative behaves. In what ways is the same as,
        // and different from, the solution above (using a timeWindowAll)?

        // DataStream<Tuple3<Long, Long, Float>> hourlyMax = hourlyTips
        // .keyBy(0)
        // .maxBy(2);

        printOrTest(hourlyMax);

        // execute the transformation pipeline
        env.execute("Hourly Tips (java)");
    }

    /*
     * Wraps the pre-aggregated result into a tuple along with the window's timestamp and key.
     */
    public static class AddTips
            extends ProcessWindowFunction<TaxiFare, Tuple3<Long, Long, Float>, Long, TimeWindow> {
        @Override
        public void process(Long key, Context context, Iterable<TaxiFare> fares,
                Collector<Tuple3<Long, Long, Float>> out) throws Exception {
            Float sumOfTips = 0F;
            for (TaxiFare f : fares) {
                sumOfTips += f.tip;
            }
            out.collect(new Tuple3<>(context.window().getEnd(), key, sumOfTips));
        }
    }
}
